PLant Lice INJURING FOLIAGE AND FRUIT OF THE APPLE 705 
In comparing the reproductive capacity of this generation with that of 
the stem mothers, it will be observed that the period of reproductive 
activity is shorter, the average daily number of young produced is 
greater, and the total number of young is less. The total length of life 
is considerably shorter. 
Description of stages 
No attempt is made in this or in the following generations to describe 
the nymphal stages. Only the mature forms of each generation are 
described. 
Apterous female, second generation In color markings, form, and 
size, this insect does not differ in any material respect from the apterous 
female of the third generation, which is described in detail on page 708. 
Fig. 114. ANTENNAE OF VARIOUS FORMS 
A, Aphis pomi, winged viviparous female; B, A. avenae, spring migrant; C, A. sorbi, spring migrant; 
D, A. sorbi, apterous female on plantain E, A. pomi, apterous female, summer form 
